Signaling system for railroads



Feb. 3, 1938. J. E WALLING SIGNALING SYSTEM FOR RAILROADS Filed NOV- & 1936 Patented Feb. 1, 1938 UNITED STATES PATEN? FFIE Joseph E. Willing, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application November 6, 1936, Serial No. 169,517

9 Claims.

This invention relates to signaling systems for railroads of the so called coded track circuit type, and more particularly to a system in which the trafilc governing apparatus is controlled by energy from the track rails without the use of line wires.

It is proposed in accordance with this invention to provide a simpleand elfective organization of relays and circuits for controlling the operation of wayside signals upon the approach of a train; more specifically an approach lighting relay is provided which picks up when a train enters its block, stays up as the train progresses through the block despite the inclusion of a coding contact in series with the relay, and releases upon the train entering the next block in advance.

Variousadvantages, purposes and characteristic features of this invention will appear as the description progresses, reference being made to the accompanying drawing, showing, solely by way of example and in no manner in a limiting sense, one form which the invention may assume.

Referring to the accompanying drawing, the invention is shown applied to a stretch of single track over which traffic moves in the direction indicated by the arrow. The rails 4 of thetrack- Way are divided in insulated joints 5 into a plurality of track sections or blocks, the complete apparatus for only one signal location being shown in the drawing.

In considering the organization of parts associated with each block in accordance with this invention, corresponding devices for the blocks l and 2 shown are given corresponding numbers with distinctive prefixes. Each track section is provided with a code following track relay OFT connected across the rails at the entrance end of the block and a two winding approach lighting relay AL having its upper winding connected, in series with a track battery B, a limiting resistance LR and a front contact 6 of a coded repeating relay CPR, across the exit end of the block.

The code following relay CFT operates suitable decoding means to selectively energize code responsive or decoder relays R188 and R15. This decoding means may take any suitable form but as shown comprises a transformer l, with its primary having a mid tap connected to one terminal, of a suitable source of direct current, the terminals of said primary being connected to the other, terminal of the same source of direct current through front and back contacts 8 of the code following relay CFT. The

two secondaries of transformer 'i are connected through double wave rectifiers 9 to the respective decoder relays R'EE and R183, with condensers 11] in the input circuits of these rectifiers proportioned to allow maximum uni-directional current for the energization of the decoder relays to flow when the code following relay CFT is energized and deenergized at the rate of and times per minute respectively, all in a manner characteristic of decoding means of this type, as shown and described, for example, in the patent to W. D. Hailes, No. 1,852,409, dated April 5, 1932, for a Locomotive equipment.

The decoder relays R15 and R180 for each block control the indications of a wayside block signal S at the entrance to the corresponding wayside block, a signal of the color light type being illustrated, with control circuits governed by front and back contacts l1 and 52 of said decoder relaysv These decoder relays also control through their contacts 13 and M a yellow and green repeater relay YGP which relay, in turn, controls the operation of the coding apparatus associated with the block to the rear.

The coding apparatus at the exit end of each block comprises two coders or modulators of suitable construction, arranged to intermittently close contacts at the different code rates; and since it is assumed that the track circuit is to be operated by direct current each coder is preferably in the form of a device having an oscillating and vibrating member operated by electro-magnets operated by direct current and actuating contacts, as distinguished from a coder driven by a polyphase or synchronous motor such as is commonly used where alternating current is available. One form of oscillatory coder of the type contemplated is disclosed, for example, in the patent to P. N. Bossart, No. 1,858,876, dated May 17, 1932. For convenience in explanation it is assumed that two codes, of rates of '75 and 180 per minute, will be used, which however are mere- 1y typical for this purpose. These codes are produced by coders or modulators, diagrammatically illustrated as comprising magnets M75 and M180 respectively operating contacts C75 and C180.

The operating characteristics of the approach lighting relay AL at the exit end of each block are so adjusted or selected that, with no train present in a block, the track circuit current-flowing from battery B through the upper winding of relay AL and the code following relay CFT in series is not sufficient to attract the armature of this relay. However, when a train enters a track section the shunting sheet of the Wheels and axles increases the current through the upper winding of relay AL to the extent that this relay attracts its armature.

Each relay AL is provided with a stick circuit including its lower winding, its own front contact l5 and a front contact I6 of the YGP relay for the block next in advance. The relays AL and YGP also provide for approach lighting of signals S.

The various circuits are shown conventionally, with the symbols and indicating the opposite terminals of the battery, or other suitable source of direct current. The details of these circuit connections are more conveniently considered in describing the operation of the system.

In explaining the operation of the system upon the approach of a train to display the proper wayside indications, it will be assumed that the parts located at the exit and entrance ends of adjacent blocks I and 2 respectively are in the positions and conditions shown in the accompanying drawing, which positions they will assume provided a block is unoccupied and the two blocks next in advance are unoccupied.

Assuming that no trains are present, under these conditions, coder MISll at the exit end of each block is energized, thereby operating its coding contact CI8il to intermittently energize the code repeater relay CPR. The intermittent energization of relay CPR operates its contact B-to apply energy from battery B at the 180 code rate to the rails at the exit end of the corresponding block. This code energy operates the code following relay CFT at the entrance end of the block to pick up its associated decoding relay R180 which in turn picks up relay YGP. The closure of front contact I] of relay YGP starts the coder MIBU to apply the 180 code to the block in the rear, .and this procedure is repeated at the remaining blocks in the rear and therefore, with no trains present, each track circuit will be supplied with energy at the 180 code rate.

It will also be noted that with no trains present the signals G will be dark due to the fact that the signal lighting circuit for each signal is open at back contact IQ of relay YGP and front contact I8 of the approach lighting relay AL of the block in the rear.

Thus, when a train enters block I for example, with the conditions as described above, the shunting effects of the trains wheels and axles increases the current through the upper winding of approach lighting relay IAL to the extent that this relay attracts its armature and the relay is held energized through its upper winding during occupancy and while front contact 6 is closed, and also through its stick circuit, previously described regardless of contact 6. The closure of front contact I3 of relay IAL completes a circuit for lighting the green lamp at signal 28. This circuit may be traced from battery, the front contact II of relay 2RI8E], the G lamp, front contact I8 of relay IAL to battery.

When the train in question enters block 2 the approach lighting relay EAL (not shown) picks up and the same operation for lighting the green lamp at signal its (not shown) is repeated, and as the train progresses through the several blocks the same action occurs at each block, provided in each case two blocks in advance are clear.

Considering the operation of the apparatus when a train enters a block, as block 2 for example, the shunting effects of the wheels and axles deprives the code following relay ZCFT of energy causing it to close its back contact 8.

This applies steady energy to the primary of transformer '1", thereby deenergizing decoding relays 2RI80 and 2315 and the opening of front contacts I4 and I3 break the energizing circuits for relay ZYGP. When relay 2YGP releases and closes its back contact I9, a circuit is completed for lighting the red lamp at signal 23. This clr cuit may be traced from battery, back contact II of relay 2RI8B, back contact I2 of relay 2Rl5, the red lamp of signal 28, back contact I9 of relay ZYGP to battery.

The deenergization of relay ZYGP and the subsequent closing of its back contact Il energizes coder IMl? through an obvious circuit to operate the coding relay ICPR for applying energy at the code rate to block I in a manner similar to that previously described for applying the code rate. The code following relay ICFT at the entrance end of block I will now operate at the 75 code rate to pick up the code relay IR'I5 (not shown), and hence energize its associated relay EYGP (not shown) to apply the 180 code rate to the block to the rear of block I, all in a manner previously described. It is evident from the foregoing that if no trains are present all the blocks to the rear of block I will be supplied with energy at the 180 code rate.

When a train moves out of block I and occupies block 2, the current through the upper winding of the approach lighting relay IAL is reduced to its normal value, and as the relay ZYGP of block 2 is deenergized, its stick circuit is broken at contact 55 of said relay ZYGP. The IAL relay will then release its armature which will remain in its release position until the next train approaches; in other words, the coded track circuit energy supplied by battery IB is insufiicient to pick up the armature of relay IAL or hold its armature up when the relays stick circuit is broken. Also, it is evident that when a train leaves block I, the signal IS (not shown) at the entrance thereof will become dark, providing the block next in the rear is unoccupied, due to the fact that the signal lighting circuit is broken at back contact I9 of relay YGP (not shown) and front contact I8 of relay AL of the block next to the rear of block I.

A shunt circuit is provided for the upper winding of the approach lighting relays AL which is closed through a back contact 29 of the relay r YGP of the block in advance. This shunt circuit insures the armature of relay AL, as IAL, releasing and staying released as soon as the train occupying block I has entered the next block.

Otherwise with the stick circuit for the relay I AL broken at contact I6 of relay LYGP, energy at the 75 code rate would cause intermittent pick up and release of relay IAL until the train in question had completely vacated block I.

The invention as illustrated provides for the control of the indications of wayside signals, but the same coded track circuit energy may be utilized for a train control or cab signal system. When a train enters a block, a code relay CPR continues to operate, thereby maintaining coding of the track rail current, even though such coded current is unnecessary for the purpose of controlling the indication of the wayside signal at the entrance to the occupied block, this signal indicating stop. As shown, the track rail current is pulsed or interrupted uni-directional current and locomotive equipment can be used which is adapted to respond to such rail current, in the manner disclosed, for example, in the patent to W. D. Hailes, 'No. 1,914,329, granted June 13, 1933.

If desired, alternating current of a suitable frequency, such as 100 cycles, may be superimposed on the pulsed'direct current for train control or cab "signal purposes and in this'connection the back contact 6 of the code relay CPR may be utilized to provide a substantially closed track circuit, that is, one closed all the time except when contact 6 is moving from one point to the other, it being understood that the alternating current would be applied between contact 6 and the track rails.

These and various other adaptations and applications of the invention have not been specifically illustrated, but it should be recognized that the approach control means of this invention may be utilized in connection with various types and forms of systems employing coding apparatus.

The above rather specific description of one form of the present invention is given solely by way of example, and is not intended, in any manner whatsoever, in a limiting sense. It is also to be understood that various modifications, adaptations, and alterations may be employed in practicing the invention without in any way departing from the spirit or scope of the invention except as limited by the appended claims.

What I claim is:

1. An approach control system for coded track circuits comprising; in combination with a plurality of track sections each having a signal; a source of current and a coding device for controlling the supply of current to the track rails of the corresponding section from said source to conform with distinctive codes each comprising a plurality of current impulses, a series relay for each track section included in series with its source of current and effectively energized by the increase in the current above that normally supplied to the track rails caused by the presence of a train; said relay when effectively energized automatically initiating operation of the signal next in advance; and a stick circuit for each of said relays controlled by traffic in advance thereof for maintaining said relay energized While said source of current is, between code impulses, temporarily disconnected from the track rails.

2. An approach control system for coded track circuits comprising; in combination with a plurality of track sections each having a signal; a source of current and a coding device for controlling the supply of current to the track rails of the corresponding section from said source to conform with distinctive codes; a series relay for each track section included in series with its source of current and effectively energized by the increase in the current supplied to the track rails caused by the presence of a train; said relay when effectively energized automatically initiating operation of the signal next in advance; and a stick circuit for each of said relays, to maintain it energized in spite of interruption of the track circuit by said coding device, controlled by trafiicconditions in advance to remain closed unless the block next in advance is occupied.

3. An approach control system for coded track circuits comprising, in combination with a plurality of track sections each having a signal, a source of current and a coding device for controlling the supply of current to the track rails of the corresponding section from said source to conform with distinctive codes, a series relay for each track section included in series with its source of current and effectively energized bythe increase in the current above that normally supplied to the track rails and caused by the pres- L ence of a train, said relay when effectively energized automatically initiating operation of the signal next in advance, and a stick circuit for each of said relays controlled by traflic conditions in advance to remain closed regardless of source of current and effectively energized bythe increase in the current above that normally supplied to the track rails and caused by the presence of a train, said relay when effectively energized automatically initiating operation of the signal next in advance, a signal repeating relay energized except when the signal is at stop, and a stick circuit for each of said series relays including a front point of the signal repeating relay for the track section next in advance,

whereby said series relay is maintained energized in spite of intermittent deenergization of the track circuit by said coding device.

5. An approach control system for coded track circuits comprising, in combination with a plurality of track sections each having a signal, a

source of current and a coding device for interrupting the supply of current to the track rails of the corresponding section supplied from said source to conform with distinctive codes, a series relay for each track section having one winding included in series withits source of current and effectively energized by the increase in current above that normally supplied to the track rails and caused by the presence of a train, said relay when eifectively energized automatically initiating operation of the signal next in advance, a signal repeating relay energized except when the signal is at stop, a stick circuit for another winding of each of said series relays including a front point of the signal repeating relay for the track section next in advance, and a shunt connected across the said one winding of each series relay and closed upon the opening of the said stick circuit, whereby each of said series relays is assured of being deenergized when its stick circuit is opened.

6. An approach control system for coded track circuits comprising, in combination with a series of track sections each having a signal, a source of current and a coding device for controlling the supply of current to the track rails of the corresponding section from said source to conform with distinctive codes, a series relay for each track section included in series with its source of current and effectively energized by the increase above normal of the current normally supplied to the track rails caused by the presence of a train, said relay when effectively energized automatically initiating operation of the signal next in advance, a signal repeating relay energized except when the signal is at stop, a stick circuit for each of said series relays including a front point of the signal repeating relay for the track section next in advance, and a shunt connected across the series relay and closed through a back point of the signal repeater relay of the section next in advance, whereby each of said series relays is assured of being deenergized when its stick circuit is broken.

7. An approach control system for coded track circuits comprising, in combination with a series of track sections each having a signal, a source of current and a coding device for controlling the supply of current to the track rails of the corresponding section from said source by intermittent interruptions of the track circuit to conform with distinctive codes, a series relay for each track section included in series with its source of current, said series relay normally assuming its deenergized condition and assuming its energized condition upon increase of the track circuit current caused by the presence of a train, said relay when in its energized condition automatically initiating operation of the signal next in advance, a stick circuit for each of said relays controlled by traific conditions in advance to remain closed unless the block next in advance is occupied, and a shunt connected across the series relay and closed upon occupancy of the block next in advance, whereby said series relay will when once in its energized condition remain energized in spite of intermittent interruption of said track circuit during occupancy of said section so long as said block next in advance is unoccupied but will be deenergized upon occupancy of said block next in advance.

8. In a railwaysignaling system of the coded track circuit type, the combination with a railway track divided into blocks by insulating joints, a track circuit for each block including a code following track relay and a source of current, a coding contact in each track circuit at the source end of such track circuit for intermittently opening said track circuit to characterize a code, a series relay included in series with each source adjusted to normally assume a deenergized condition and to assume an energized condition upon occupancy of the track circuit at least during the period when the associated coding contact is closed, means for holding said series relay energized during open periods of said coding contact and during unoccupancy of the block next in advance and for shunting said series relay during occupancy of the next block in advance, and a signal at the entrance to the next block in advance having a control circuit including a front contact of said series relay and controlled by the track relay of the next block in advance.

9. In a railway signaling system, the combination with a railway track divided into blocks by insulating joints, a track circuit for each block including in series a track relay at the entrance end and a source of current at the exit end, a

independently of the condition of the series relay of the next block in the rear and controlled by trafiic conditions of the associated block, whereby approach lighting is provided for the signal when indicating clear and the stop signal is lighted independently of the approach of a train so that failure of the approach lighting control will not result in a dark stop signal.

JOSEPH E. WILLING. 

